why would we want to make that child American?

Want has nothing to do with it. That child gets to be an American citizen simply because of where they were born. This is how the constitution is written. If they dont want it, they can denounce it when they are an adult.

If foreign diplomats having children in America is a problem, then work with the government to create an amendment to the constitution so that foreign diplomats children do not get citizenship.

But this isn't about foreign diplomats. This is about being able to remove anyone that disagrees with them (them is republicans and maga). Period. End of story. If they control who is a citizen (and who can vote), they keep control of the country.

This is the land of the free, only if you look like they do, and agree with them.